Soon, smart ovenware to speed up microwave cooking

Published: Thursday, July 17, 2008, 14:04 [IST]

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London, July 17 : Cooking your food in the microwave is set to get faster what with smart baking dishes made from an exotic ceramic material being developed. What's more, the dishes would also reduce the energy consumption during cooking.

Usually, microwave ovens cook food via an alternating electric component that causes any molecules with a positive charge at one end and a negative charge at the other, such as water, to rotate and align themselves with the field.

This rotation of water moves other nearby molecules, which in turn are set in motion and thus causes the food to heat up. However, being "transparent" to microwaves, microwave ovenware ends up getting heated up only through conduction as it touches the hot food. This implies that the food dissipates some heat to its container.

But this loss of heat can be reversed via ovenware that is directly heated by microwaves by conductively heating the food instead, which would improve the efficiency of microwave cooking.

But now, Sridhar Komarneni at Pennsylvania State University, together with Hiroaki Katsuki and Nobuaki Kamochi at the Saga Ceramic Research Laboratory in Saga, Japan, have developed a new ceramic with microwave-absorbing properties.

The researchers made the ceramic by first taking up powdered petalite, a lithium-rich mineral, and mixing it with a small quantity of magnetic iron oxide. This powder was then dried and fired in a kiln for 5 hours, before sintering it at 1250°C to create an iron oxide-petalite foam suitable for use as a microwave ceramic.

On interaction with the microwaves' electric field, this iron oxide component and heats up rapidly while the insulating petalite component aids in retaining that heat even after the oven is switched off.

When the researchers tested their new foam against standard porcelain ovenware in a 600-watt microwave oven, they discovered that after 70 seconds of power, the porcelain turned to 50-60 degree Celsius, but the new foam had its temperature reaching over 200 degree Celsius.

In fact, the foam constantly gained temperature for another 30 seconds after the power was switched off, and reached the peak at 294 degree Celsius.

And Komarneni said that this was because it takes a few seconds for the heat to spread from the iron oxide component throughout the foam.

"The microwave-ware saves about 50% energy compared to the conventional microwave ware," The New Scientist quoted him, as saying.

When the researchers constructed a ceramic rice cooker using the new foam, it took just 10 minutes for preparing rice as against the usual 20-30 minutes using conventional ovenware.

Komarneni said the new ovenware would soon be available in the market as the new material is already being commercialised by a company in Japan.